It is foolish attempt to imagine agriculture without cows. Mother गौ (Gau) play several roles in maintaining eco system. One of the roles she play with her children’s help is to maintain water levels and nutrients for land. It is via Homa/Agnihotra.
Dung ash is sacred in Hinduism. It is gold. (Already covered in old notes. Search ‘dung ash’)
Here are some more papers.
When fire occurs naturally in the wild, it is good for future of the flora and fauna. But since we now live in sentimental world with no or little rationality left, we curse every natural phenomenon and in same breathe, we blissfully enjoy man-made destructions all around by keeping blind eyes.
I do remember some tribal igniting fire in certain part of Satpuda jungles. They told me that this helps to maintain jungle. They did not know, how part. Same is the role of their fire rituals. Same is the role of Agnihotra for our farms and gardens.
Read this to realize biological importance of charcoal and importance of fire in jungle ecosystem.
Wildfire-produced charcoal directly influences nitrogen cycling in ponderosa pine forests 
Fire is the primary form of disturbance in temperate and boreal forest ecosystems. However, our knowledge of the biochemical mechanisms by which fire stimulates forest N cycling is incomplete. Charcoal is a major byproduct of forest fires and is ubiquitous in soils of most forest ecosystems, yet the biological function of charcoal in soils of forest ecosystems has been greatly overlooked. We conducted a suite of laboratory experiments on soils from ponderosa pine (Pinus ponderosa Laws) forests to determine the influence of charcoal on soil N dynamics and in particular, nitrification. The addition of NH4(+) to forest soils had absolutely no effect on nitrification demonstrating that this process is not substrate limited. The amendment of these soils with NH4(+) and field collected charcoal (1% w/w) significantly increased the nitrification potential, net nitrification, gross nitrification, and decreased the solution concentrations of plant secondary compounds (phenolics). Charcoal had no effect on nitrification in soils (from a grassland site) that had naturally high rates of nitrifier activity. The increase in gross nitrification in forest soils and lack of effect on grassland soils suggests that charcoal may alleviate factors that otherwise inhibit the activity of the nitrifying microbial community in forest soils. These results reveal the biological importance of charcoal and advance our mechanistic understanding of how fire drives nutrient cycling in te
Long term effects of manure, charcoal and mineral fertilization on crop production and fertility on a highly weathered Central Amazonian upland soil
The Charcoal Vision: A Win–Win–Win Scenario for Simultaneously Producing Bioenergy, Permanently Sequestering Carbon, while Improving Soil and Water Quality
Application of charcoal to soils is hypothesized to increase bioavailable water, build soil organic matter, enhance nutrient cycling, lower bulk density, act as a liming agent, and reduce leaching of pesticides and nutrients to surface and ground water. The half-life of C in soil charcoal is in excess of 1000 yr. Hence, soil-applied charcoal will make both a lasting contribution to soil quality and C in the charcoal will be removed from the atmosphere and sequestered for millennia.
Charcoal Volatile Matter Content Influences Plant Growth and Soil Nitrogen Transformations